U.S. patent application number 10/097771 was filed with the patent office on 2002-11-28 for ultraviolet irradiation apparatus and method of forming cured coating film using the apparatus.
This patent application is currently assigned to GEN Maintenance Technology Inc.. Invention is credited to Kanie, Takashi, Yamamura, Nobuo.
Application Number | 20020175299 10/097771 |
Document ID | / |
Family ID | 27482113 |
Filed Date | 2002-11-28 |
United States Patent
Application |
20020175299 |
Kind Code |
A1 |
Kanie, Takashi ; et
al. |
November 28, 2002 |
Ultraviolet irradiation apparatus and method of forming cured
coating film using the apparatus
Abstract
An ultraviolet irradiation apparatus for curing an ultraviolet
curable coating agent applied to a substrate, by irradiating an
ultraviolet light to the ultraviolet curable coating agent, which
includes a low-pressure mercury lamp as a light source. According
to the present invention, the problems associated with the use of
an ultraviolet irradiation apparatus, whose light source is a
high-pressure mercury lamp, can be solved, such as the need of a
high voltage power source, degradation of quality, potential hazard
to operators and the like. The present invention also provides a
method of forming a cured coating film having the same properties
as achieved by the use of a high-pressure mercury lamp, such as
resistance to stain, adhesion to substrate and the like. This
method requires a shorter time for curing of a unit area of the
film as compared to the use of a high-pressure mercury lamp (100 V
type). Accordingly, the present invention is particularly useful
for floor surfaces of gymnasiums, classrooms, department stores,
offices, stores, showrooms and the like.
Inventors: |
Kanie, Takashi;
(Tsushima-shi, JP) ; Yamamura, Nobuo;
(Tsushima-shi, JP) |
Correspondence
Address: |
LEYDIG VOIT & MAYER, LTD
TWO PRUDENTIAL PLAZA, SUITE 4900
180 NORTH STETSON AVENUE
CHICAGO
IL
60601-6780
US
|
Assignee: |
GEN Maintenance Technology
Inc.
73, Aza Naknoori, Kamori-cho
Tsushima-shi
JP
496-0005
|
Family ID: |
27482113 |
Appl. No.: |
10/097771 |
Filed: |
March 14, 2002 |
Current U.S.
Class: |
250/504R |
Current CPC
Class: |
B05D 3/067 20130101;
C09D 133/14 20130101; C09D 175/16 20130101; C08L 2312/00
20130101 |
Class at
Publication: |
250/504.00R |
International
Class: |
G01J 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 14, 2001 |
JP |
072686/2001 |
Mar 19, 2001 |
JP |
079336/2001 |
Dec 27, 2001 |
JP |
398486/2001 |
Dec 28, 2001 |
JP |
400816/2001 |
Claims
What is claimed is:
1. An ultraviolet irradiation apparatus for curing an ultraviolet
curable coating agent applied on a substrate by irradiating an
ultraviolet light to the ultraviolet curable coating agent,
comprising a low-pressure mercury lamp as a light source.
2. The ultraviolet irradiation apparatus of claim 1, which is
moveable and which comprises a power source section equipped with a
wheel, and a light source section electrically connected to the
power source section that emits an ultraviolet light upon supply of
electricity from the power source section.
3. The ultraviolet irradiation apparatus of claim 2, wherein the
power source section is supplied with an input voltage of less than
200 V and an input current of not more than 20 A.
4. The ultraviolet irradiation apparatus of claim 2, wherein the
low-pressure mercury lamp has an input power per unit size of not
less than 1 W/cm.
5. The ultraviolet irradiation apparatus of claim 2, wherein the
light source section and the power source section are electrically
connected with a detachable electric cord.
6. The ultraviolet irradiation apparatus of claim 5, wherein the
light source section can be placed on the power source section.
7. The ultraviolet irradiation apparatus of claim 2, which further
comprises, in addition to said light source section comprising a
low-pressure mercury lamp as a light source, a second light source
section that emits an ultraviolet light having a dominant
wavelength of not less than 320 nm as a light source, said second
light source section is disposed such that the ultraviolet light
having a wavelength of not less than 320 nm reaches the ultraviolet
curable coating agent after arrival of the ultraviolet light from
said low-pressure mercury lamp.
8. The ultraviolet irradiation apparatus of claim 7, wherein the
ultraviolet light source having a dominant wavelength of not less
than 320 nm is disposed on both sides of the light source
section.
9. The ultraviolet irradiation apparatus of claim 7, wherein the
light source having a dominant wavelength of not less than 320 nm
is disposed at an upper side or in front of the low-pressure
mercury lamp on a forward end of the light source section.
10. A method of forming a cured coating film, comprising the steps
of (a) coating a substrate with an ultraviolet curable coating
agent comprising a photopolymerization initiator and a
photopolymerizable resin comprising a urethane(meth)acrylate resin,
and (b) irradiating an ultraviolet light using the ultraviolet
irradiation apparatus of claim 1, to cure the coating film.
11. The method of forming the cured coating film according to claim
10, wherein the urethane(meth)acrylate resin is produced by a
urethane reaction using an aluminum compound as a catalyst.
12. The method of forming the cured coating film according to claim
10, wherein the ultraviolet curable coating agent is applied to a
substrate such that the film has a thickness after curing of not
less than 4 .mu.m and not more than 70 .mu.m.
13. The method of forming the cured coating film according to claim
10, wherein the ultraviolet curable coating agent is applied to a
substrate such that the film has a thickness after curing of not
less than 7 .mu.m and not more than 70 .mu.m.
14. The method of forming the cured coating film according to claim
10, wherein the ultraviolet curable coating agent is applied to a
substrate after application of a primer thereto.
15. The method of forming the cured coating film according to claim
10, wherein the ultraviolet curable coating agent is aqueous.
16. The method of forming the cured coating film according to claim
10, wherein the ultraviolet curable coating agent is applied to a
floor surface, after which the ultraviolet light is irradiated
thereon using the ultraviolet irradiation apparatus of claim 2 to
cure the coating agent.
17. The method of forming the cured coating film according to claim
10, further comprising plural times of UV irradiation of a coating
film having a UV insufficient area produced by the UV irradiation,
using a moveable ultraviolet irradiation apparatus.
18. The method of forming the cured coating film according to claim
17, wherein the UV irradiation is applied within 15minutes from a
previous UV irradiation.
19. The method of forming the cured coating film according to claim
17, wherein the UV irradiation is applied within 5 minutes from a
previous UV irradiation.
20. A urethane(meth)acrylate resin obtained by reacting an
isocyanate compound and a hydroxyl compound using an aluminum
compound as a catalyst.
21. A ultraviolet curable coating agent comprising the
urethane(meth)acrylate resin of claim 20.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] The present invention relates to an ultraviolet irradiation
apparatus (particularly, moveable ultraviolet irradiation
apparatus) used for UV irradiation of floors of a building, such as
gymnasium, classroom, department store, office, store, showroom,
house and the like, for the purpose of curing an ultraviolet
curable coating agent applied at the worksite.
[0002] More particularly, the present invention relates to a method
for forming a cured coating film using the ultraviolet irradiation
apparatus.
BACKGROUND OF THE INVENTION
[0003] A coating film made from an ultraviolet curable coating
agent is mainly cured using an ultraviolet irradiation apparatus
using a high-pressure mercury lamp and/or middle-pressure mercury
lamp having a high calorific value as a light source Particularly
for the application at work site, a moveable ultraviolet
irradiation apparatus having a high-pressure mercury lamp and/or a
middle-pressure mercury lamp as a light source has been used.
[0004] The moveable ultraviolet irradiation apparatus basically has
a power source section equipped with wheels, and a light source
section electrically connected to the power source Section to emit
ultraviolet light in response to a power supply from the power
source section. In conventional moveable ultraviolet irradiation
apparatuses, a high-pressure mercury lamp and/or a middle-pressure
mercury lamp are/is generally used as a light source section,
because these lamps provide superior work efficiency, as evidenced
by high moving speed of the apparatus realized by the short time
necessary for curing a coating agent, increased irradiation width
of ultraviolet light and the like.
[0005] When the above-mentioned high-pressure mercury lamp and/or
middle-pressure mercury lamp are/is used as a light source,
however, a greater input power is required than does the use of a
low-pressure mercury lamp and the like. In the conventional
moveable ultraviolet irradiation apparatuses, the use of a typical
100V single-phase alternating current (AC) power source makes work
time longer, because it limits the size and number of the lamp,
thereby restricting the moving speed of the apparatus and allowing
irradiation of only a small area. To avoid such problems, a 200V
three-phase AC power source has been generally used.
[0006] The 200V three-phase AC power source, nevertheless, is set
in specific sites, such as the basement floor of a building and the
like, and a 100V single-phase AC power source is normally installed
on each floor. This in turn means that coating on each floor of a
building using an ultraviolet curable coating agent requires
bringing a power source of a moveable ultraviolet irradiation
apparatus up from, for example, the basement floor. When a 200v
three-phase AC power source is used, therefore, the work site and
the power source may be located far from each other. Since these
two need to be connected electrically with a long power cord, the
workability becomes poor.
[0007] Moreover, since a conventional moveable ultraviolet
irradiation apparatus requires a high power as mentioned above, the
temperature of the light source becomes considerably high, which in
turn induces high thermal radiation during the use of ultraviolet
light. When the above-mentioned coating is applied to a floor
material made from a resin having generally low heat resistance,
such as vinyl chloride resin, polyolefin resin, polyester resin and
the like, the heat sometimes burns the floor surface, causes
thermal deformation (twist, bend, warp etc.) of the floor material
and/or coating film and produces cracks etc., easily degrading the
quality. To solve these problems, a cold mirror may be used for the
apparatus and the cooling method of the apparatus may be devised,
but these approaches would make the apparatus expensive. In
addition, the worker using the apparatus is at risk of injury,
because the worker may inadvertently touch the light source section
during or immediately after UV irradiation and get burnt.
[0008] Conventional moveable ultraviolet irradiation apparatuses
are also inconvenient in that the apparatus as a whole becomes
bulky and heavy, because it requires a large capacitance, making
the power source section bigger. The detachment/attachment of a
high voltage electric cord is generally unpreferable from the
safety aspect. Thus, the power source section and the light source
section should be constantly kept in electrical connection, which
makes transport etc. of the apparatus difficult.
[0009] When a low-pressure mercury lamp is used as a light source,
the coating film may not be sufficiently cured. Thus, curing to a
sufficient level may take longer than when a 200V high-pressure
mercury lamp is used as a light source. On the contrary, a
low-pressure mercury lamp does not require a high voltage power
source, because the necessary capacitance is not so high as that
for a high-pressure mercury lamp. Furthermore, since a low-pressure
mercury lamp emits only a small amount of heat, it is safe for the
operator. Even if irradiation is applied longer than the
predetermined time, the lamp does not burn the substrate and/or
coating film, does not cause deformation (twist, bend, warp etc.)
and does not produce cracks etc. Consequently, a low-pressure
mercury lamp does not easily cause degradation of the quality.
SUMMARY OF THE INVENTION
[0010] It is therefore an object of the present invention to
provide an ultraviolet irradiation apparatus (particularly a
moveable ultraviolet irradiation apparatus) that uses only a
smaller input power than before, is capable of improving
workability and safety and that permits miniaturization and light
weight apparatus.
[0011] Another object of the present invention is to solve the
problems associated with the use of an ultraviolet irradiation
apparatus, whose light source is a high-pressure mercury lamp, such
as the need of a high voltage power source, degradation of quality,
potential hazard to operators and the like, and provide a method of
forming a cured coating film having the same properties as achieved
by the use of a high-pressure mercury lamp, such as resistance to
stain, adhesion to substrate and the like, and requiring a shorter
time for curing of a unit area of the film as compared to the use
of a high-pressure mercury lamp (100 V type).
[0012] The present inventors have found that a cured coating film
obtained by applying an ultraviolet curable coating agent
containing a photopolymerization initiator and a photopolymerizable
resin containing a urethane(meth)acrylate resin to a substrate and
irradiating the agent with ultraviolet light using an ultraviolet
irradiation apparatus, whose light source is a low-pressure mercury
lamp, to cure the coating film is free of problems associated with
the use of an ultraviolet irradiation apparatus, whose light source
is a high-pressure mercury lamp, such as the need of a high voltage
power source, degradation of quality, potential hazard to operators
and the like, has the same properties as achieved by the use of a
high-pressure mercury lamp, such as resistance to stain, adhesion
to substrate and the like, and requires a shorter time for curing
of a unit area of the film as compared to the use of a
high-pressure mercury lamp (100 V type), which led to the
completion of the present invention.
[0013] During UV irradiation of a coating film, the ultraviolet
light may leak from an ultraviolet irradiation apparatus. However,
the amount of the leaked ultraviolet light is not sufficient to
cure the coating film. Thus, the area exposed to the leaked
ultraviolet light is insufficiently irradiated with UV. This UV
insufficient area and the area exposed to a sufficient amount of
ultraviolet light for curing of the coating film (UV irradiation
area) are located near. As a result, defects of coating film occur,
such as appearance of patterns of tortoise shell (hereinafter to be
referred to as Tortoiseshell Pattern), crepe pattern (hereinafter
to be referred to as Wrinkle), fine concavoconvex pattern
(hereinafter to be referred to as Fog) and the like. To solve this
problem, the present invention proposes use of a
urethane(meth)acrylate resin as an ultraviolet curable coating
agent, which is obtained by urethane reaction using an aluminum
compound as a catalysts or application of plural cycles of UV
irradiation, within a given length of time, of a coating film
having a UV insufficient area produced by irradiation of leaked UV
light, thereby providing a superior effect of suppressing the
occurrence of defects of coating film, such as Tortoiseshell
Pattern, Wrinkle, Fog and the like.
[0014] Accordingly, the present invention provides the following 1)
to 21).
[0015] 1) An ultraviolet irradiation apparatus for curing an
ultraviolet curable coating agent applied on a substrate by
irradiating an ultraviolet light to the ultraviolet curable coating
agent, comprising a low-pressure mercury lamp as a light
source.
[0016] 2) The ultraviolet irradiation apparatus of the
above-mentioned 1) which comprises a power source section equipped
with a wheel, and a light source section electrically connected to
the power source section that emits an ultraviolet light upon
supply of electricity from the power source section
[0017] 3) The ultraviolet irradiation apparatus of the
above-mentioned 2), wherein the power source section is supplied
with an input voltage of less than 200 V and an input current of
not more than 20 A.
[0018] 4) The ultraviolet irradiation apparatus of the
above-mentioned 2), wherein the low-pressure mercury lamp has an
input power per unit size of not less than 1 W/cm.
[0019] 5) The ultraviolet irradiation apparatus of the
above-mentioned 2), wherein the light source section and the power
source section are electrically connected with a detachable
electric cord.
[0020] 6) The ultraviolet irradiation apparatus of the
above-mentioned 5), wherein the light source section can be placed
on the power source section.
[0021] 7) The ultraviolet irradiation apparatus of the
above-mentioned 2), which further comprises, in addition to the
above-mentioned light source section comprising a low-pressure
mercury lamp as a light source, a second light source section that
emits an ultraviolet light having a dominant wavelength of not less
than 320 nm as a light source, said second light source section is
disposed such that the ultraviolet light having a wavelength of not
less than 320 nm reaches the ultraviolet curable coating agent
after arrival of the ultraviolet light from the above-mentioned
low-pressure mercury lamp.
[0022] 8) The ultraviolet irradiation apparatus of the
above-mentioned 7), wherein the ultraviolet light source having a
dominant wavelength of not less than 320 nm is disposed on both
sides of the light source section.
[0023] 9) The ultraviolet irradiation apparatus of the
above-mentioned 7), wherein the light source having a dominant
wavelength of not less than 320 nm is disposed at an upper side or
in front of the low-pressure mercury lamp on a forward end of the
light source section.
[0024] 10) A method of forming a cured coating film, comprising the
steps of
[0025] (a) coating a substrate with an ultraviolet curable coating
agent comprising a photopolymerization initiator and a
photopolymerizable resin comprising a urethane(meth)acrylate resin,
and
[0026] (b) irradiating an ultraviolet light using the ultraviolet
irradiation apparatus of the above-mentioned 1), to cure the
coating film.
[0027] 11) The method of forming the cured coating film according
to the above-mentioned 10), wherein the urethane(meth)acrylate
resin is produced by a urethane reaction using an aluminum compound
as a catalyst.
[0028] 12) The method of forming the cured coating film according
to the above-mentioned 10), wherein the ultraviolet curable coating
agent is applied to a substrate such that the film has a thickness
after curing of not less than 4 .mu.m and not more than 70
.mu.m.
[0029] 13) The method of forming the cured coating film according
to the above-mentioned 10), wherein the ultraviolet curable coating
agent is applied to a substrate such that the film has a thickness
after curing of not less than 7 .mu.m and not more than 70
.mu.m.
[0030] 14) The method of forming the cured coating film according
to the above-mentioned 10), wherein the ultraviolet curable coating
agent is applied to a substrate after application of a primer
thereto.
[0031] 15) The method of forming the cured coating film according
to the above-mentioned 10), wherein the ultraviolet curable coating
agent is aqueous.
[0032] 16) The method of forming the cured coating film according
to the above-mentioned 10), wherein the ultraviolet curable coating
agent is applied to a floor surface, after which the ultraviolet
light is irradiated thereon using the ultraviolet irradiation
apparatus of claim 2 to cure the coating agent.
[0033] 17) The method of forming the cured coating film according
to the above-mentioned 10), further comprising plural times of UV
irradiation of a coating film having a UV insufficient area
produced by the UV irradiation, using a moveable ultraviolet
irradiation apparatus.
[0034] 18) The method of forming the cured coating film according
to the above-mentioned 17), wherein the UV irradiation is applied
within 15 minutes from a previous UV irradiation.
[0035] 19) The method of forming the cured coating film according
to the above-mentioned 17), wherein the UV irradiation is applied
within 5 minutes from a previous UV irradiation.
[0036] 20) A urethane(meth)acrylate resin obtained by reacting an
isocyanate compound and a hydroxyl compound using an aluminum
compound as a catalyst.
[0037] 21) An ultraviolet curable coating agent comprising the
urethane(meth)acrylate resin of the above-mentioned 20).
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] FIG. 1 is a simplified side view of a preferable first
embodiment of the moveable ultraviolet irradiation apparatus 1 of
the present invention.
[0039] FIG. 2 is a top view of the moveable ultraviolet irradiation
apparatus 1 of FIG. 1.
[0040] FIG. 3 is a simplified side view of a moveable ultraviolet
irradiation apparatus 1 during transport without irradiation of
ultraviolet light.
[0041] FIG. 4 is a simplified side view of a preferable second
embodiment of the moveable ultraviolet irradiation apparatus 21 of
the present invention.
[0042] FIG. 5 is a top view of the moveable ultraviolet irradiation
apparatus 21 of FIG. 4.
[0043] FIG. 6 is a simplified cross-sectional view of a handy type
light source section 31 of the present invention. In the Figure, 1
is a moveable ultraviolet irradiation apparatus, 2 is a power
source section and 3 is a light source section.
DETAILED DESCRIPTION OF THE INVENTION
[0044] The present invention is explained in detail in the
following.
[0045] In the present specification, by the "UV irradiation area"
is meant "a coating film exposed to ultraviolet light in an amount
sufficient for curing the coating film (UV irradiation quantity of
preferably not less than 60 mJ/cm.sup.2, more preferably not less
than 150 mJ/cm.sup.2)", by the "UV insufficient area" is meant "a
coating film exposed to ultraviolet light in an amount exceeding
normally irradiated ultraviolet light but insufficient to cure a
coating film", and by the "UV unirradiation area" is meant "a
coating film free of ultraviolet light irradiation, which is
optionally exposed to ultraviolet light at a normal level (e.g.,
sunshine etc.)".
[0046] 1. Ultraviolet Irradiation Apparatus
[0047] The ultraviolet irradiation apparatus of the present
invention is characterized by the light source which is a
low-pressure mercury lamp.
[0048] Generally, a mercury lamp emits light by electrical
discharge in mercury vapor. Those having an internal pressure of
not more than 1 mmHg are referred to as low-pressure mercury lamp,
wherein most part of the optical energy are concentrated around 254
nm (253 nm-255 nm, particularly 253.7 nm), and used for a
fluorescent lamp a germicidal lamp and the like (Iwanami
Rikagakujiten, 1998, p. 683).
[0049] The low-pressure mercury lamp in the present invention means
the same as for the above-mentioned definition. As long as it emits
ultraviolet light at 253.7 nm (254 nm), it is free of any
particular limitation as to its shape, size and the like. Specific
examples include QGL-100-2X (IWASAKI ELECTRIC Co., Ltd.) and the
like. In view of curing property of a coating film, a higher output
type lamp is preferable.
[0050] The low-pressure mercury lamp has a lower calorific value
than does a high-pressure mercury lamp. It has a low risk of
burning an operator who inadvertently touched the lamp immediately
after UV irradiation. In addition, it requires smaller capacitance
and a typical 100V power source can be used for at site
application, with sufficient curability. An ultraviolet irradiation
apparatus using a low-pressure mercury lamp as a light source
provides various advantages in that a cooling system (fan and
insulating board) can be made smaller than that for an apparatus
using a high-pressure mercury lamp as a light source. As a result,
the ultraviolet irradiation apparatus as a whole becomes light
weight and its work efficiency can be improved.
[0051] As an ultraviolet irradiation apparatus, for example, a
known moveable ultraviolet irradiation apparatus disclosed in U.S.
Pat. No. 6,096,383, JP-B-2588100 and the like. The moveable
ultraviolet irradiation apparatus to be explained in detail in the
following is preferably used.
[0052] FIG. 1 is a simplified side view of a preferable first
embodiment of the moveable ultraviolet irradiation apparatus 1 of
the present invention and FIG. 2 is a top view of the moveable
ultraviolet irradiation apparatus 1 of FIG. 1. In FIG. 1 and FIG.
2, the moveable ultraviolet irradiation apparatus 1 can emit
ultraviolet light. The moveable ultraviolet irradiation apparatus 1
of the present invention is an apparatus for forming a cured
coating film on a floor surface by irradiating ultraviolet light on
the upper surface of an ultraviolet curable coating agent applied
on the floor surface. The apparatus basically comprises a power
source section 2 equipped with a wheel, and a light source section
3 electrically connected to the power source section 2 and emits
ultraviolet light upon supply of power from the power source
section 2. In the present specification, the forward direction Al
means the side on which light source section 3 of the moveable
ultraviolet irradiation apparatus 1 is disposed in a state allowing
irradiation of the ultraviolet light, and the backward direction A2
means the opposite side from the forward direction A1.
[0053] The power source section 2 has a box housing 4 and the
housing 4 contains a stabilizer (not shown) and a controller (not
shown). The power source section 2 may have, as shown in FIG. 1, a
power cord 5 to obtain power from a consent and the like as a power
source. Alternatively, a power source section such as a battery may
be installed inside the housing.
[0054] The power source section 2 comprises a wheel, specifically a
front wheel 6 to be set on the forward direction side near a lower
end of housing 4, and a rear wheel 7 to be set on the backward
direction side near the lower end of the housing 4. In the
embodiment shown in FIG. 1, the front wheel 6 and rear wheel 7 each
consists of, but not limited to, two wheels. Either wheel may
consist of a single wheel. Because the front wheel 6 and rear wheel
7 are set on a power source section 2, they do not step on the
uncured ultraviolet curable coating agent coated on a floor surface
when irradiating ultraviolet light while moving. To be specific,
the moveable ultraviolet irradiation apparatus 1 generally moves in
the direction toward the side where the light source section 3 is
set, while emitting the ultraviolet light. The wheels always follow
the path where the light source section 3 passed. As a result, the
wheel always steps on the coating film cured by UV irradiation of
the ultraviolet curable coating agent, without stepping on the
uncured ultraviolet curable coating agent. With the above-mentioned
front wheel 6 and rear wheel 7, the moveable ultraviolet
irradiation apparatus 1 is constituted to secure a smooth movement
back and forth.
[0055] The light source section 3 is electrically connected to the
above-mentioned power source section 2, and emits ultraviolet light
upon provision of electricity from the power source section 2. In
the embodiment shown in FIG. 1 and FIG. 2, the light source section
3 comprises a box cover (lamp housing) 8 having an opening to pass
the light and a light source (lamp) 9 housed in the cover 8.
[0056] The important aspect of the present invention is the use of
the above-mentioned low-pressure mercury lamp as a light source to
cure an ultraviolet curable coating agent applied to a floor
surface by irradiation of ultraviolet light. The low-pressure
mercury lamp has never been used conventionally as a light source
of a moveable ultraviolet irradiation apparatus.
[0057] The moveable ultraviolet irradiation apparatus 1 of the
present invention, which uses a low-pressure mercury lamp as a
light source 9, can decrease the power necessary for input into
power source section 2, as compared to the use of a high-pressure
mercury lamp or middle-pressure mercury lamp as a light source. In
the present invention, therefore, a moveable ultraviolet
irradiation apparatus can be realized, wherein the input voltage of
power source section is less than 200V, and the input current is
not more than 20A. In addition, using a general 100V single-phase
AC power source (receptacle of about 100V.multidot.15A) as a power
source, a moveable ultraviolet irradiation apparatus can be
realized. Unlike the conventional cases where a power sources of a
200V three-phase AC is essential, a power source is available in
each in site application, when, for example, the floor of each
floor in a building is to be coated with an ultraviolet curable
coating agent and the like, thereby improving workability.
[0058] In the present invention, a low-pressure mercury lamp is
used as a light source, as result of which calorific value at the
light source section due to irradiation of ultraviolet light be
decreased to the same level as that of fluorescent lamp. Therefore,
unlike the conventional cases where a high-pressure mercury lamp
and middle-pressure mercury lamp are used as light sources, even
when an operator inadvertently touched the light source section 3
during UV irradiation or immediately after UV irradiation, the
operator is not burnt and free of such risk. Furthermore, even when
a floor material generally having low heat resistance is to be
coated, burning of the floor surface, thermal deformation (twist,
bend, warp etc.) of a floor material and the like do not occur.
[0059] The use of a low-pressure mercury lamp as a light source 9
decreases the power to a level necessary for a fluorescent lamp
Therefore, the power source section 2 can be a miniaturized and
light weight apparatus, as compared to a conventional moveable
ultraviolet irradiation apparatus. Consequently, the ultraviolet
irradiation apparatus 1 as a whole can be made into a miniaturized
and light-weight apparatus as compared to conventional
apparatuses.
[0060] When a high-pressure mercury lamp is used as a light source,
as in the conventional ones, about 2 minutes to 6 minutes is
necessary after switching on of the power source section until the
luminance of the light source reaches a given level to irradiate
ultraviolet light. In the present invention, however, since a
low-pressure mercury lamp is used as a light source, ultraviolet
light can be irradiated within a few seconds after switching on of
the power source section. Because the time necessary before
irradiation of the ultraviolet light after supply of power to the
light source section can be shortened as compared to conventional
apparatuses, which in turn improves workability.
[0061] The low-pressure mercury lamp to be used in the present
invention preferably shows an input power per unit size (input
power per length of light emitted from light source) of not less
than 1 W/cm. When the input power per unit size is less than 1
W/cm, the time necessary for the ultraviolet curable coating agent
to be sufficiently cured after irradiation of ultraviolet light on
the ultraviolet curable coating agent applied to the floor surface
is too long, thereby unpreferably degrading the workability. By the
use of a low-pressure mercury lamp having an input power per unit
size of not less than 1 W/cm, the ultraviolet curable coating agent
can be sufficiently cured in about a few seconds after irradiation
of ultraviolet light, affording efficient coating of a
substrate.
[0062] In the present invention, the method of setting a
low-pressure mercury lamp is not particularly limited. When a
straight type low-pressure mercury lamp is used, it may be set in
the longitudinal direction (about parallel to the backward and
forward direction) or transverse direction (about perpendicular to
the backward and forward direction), or when a curved low-pressure
mercury lamp is used as shown in U.S. Pat. No. 6,207,118,B1, it may
be set in an optional direction.
[0063] FIG. 1 and FIG. 2 show an embodiment of a moveable
ultraviolet irradiation apparatus 1, wherein seven low-pressure
mercury lamps (QGL-100-2X, IWASAKI ELECTRIC CO., LTD.), each having
an effective emission length (length in the longitudinal direction
of lamp) of 64 cm and an input power of 100 W (input power per unit
size: about 1.5 W/cm) are transversely arranged (about
perpendicular to the backward and forward direction) to give a
light source 9, with which a light source section 3 is realized.
When, in such a case, ultraviolet light is irradiated on the floor
surface using a moveable ultraviolet irradiation apparatus 1, the
UV irradiation intensity (measured using irradiation intensity
meter (UVP254, IWASAKI ELECTRIC CO., LTD.) on the floor surface was
4.3 mw/cm.sup.2 (254 nm intensity) at 3.5 cm inside the cover from
the side of the cover, and 0.8 mW/cm.sup.2 (254 nm intensity) at
3.5 cm outside the cover from the side of the cover. Using an
ultraviolet irradiation apparatus 1 having a light source section 3
mounted as mentioned above, for example, ultraviolet light is
irradiated on an ultraviolet curable coating agent containing a
urethane(meth)acrylate resin to be mentioned below, so that the
thickness of the cured coating film would be 15 .mu.m. As a result,
the curing rate of about 6 /m/min can be achieved, even if the
input power is less than 100V.multidot.15A (in the above case,
substantial cure width is about 80 cm).
[0064] In the moveable ultraviolet irradiation apparatus 1, a power
source section 2 and a light source section 3 are electrically
connected by a detachable electric cord 10. In the present
invention, conventional high voltage is not transmitted from the
power source section 2 to light source section 3. When the
ultraviolet light is not irradiated (e.g., during transport to
application site, during preservation and the like), therefore,
electric cord 10 can be pulled out from power source section 2 and
light source section 3, without causing any safety problem. In the
present invention, therefore, when the above-mentioned ultraviolet
light is not irradiated, electric cord 10 can be pulled out, power
source section 2 and the light source section 3 can be separated
and the light source section 3 can be placed on the power source
section 2.
[0065] For example, in the moveable ultraviolet irradiation
apparatus 1 as shown in FIG. 1, which can irradiate ultraviolet
light, a supporting member 11 fixed on the side wall of a housing 4
of power source section 2 is inserted in a cover 8 to support the
upper wall of the cover 8 from the inside, a bolt screw is inserted
from the upper wall of the cover 8 until it reaches the supporting
member 11, thereby to fix the cover 8 and the supporting member 11.
In this way, the light source section 3 is connected to the front
of the power source section 2, at 1 cm-6 cm distant from the floor
surface. FIG. 3 is a simplified side view of the moveable
ultraviolet irradiation apparatus 1 when ultraviolet light is not
irradiated. In the embodiment of FIG. 3, the ultraviolet light that
can be irradiated in FIG. 1 and FIG. 2 has been made to be
otherwise by turning off the power switch (not shown) etc., then
electric cord 10 that electrically connects the power source
section 2 and the light source section 3 is pulled out, the light
source section 3 is separated from the power source section 2, and
the light source section 3 is placed on the power source section
2.
[0066] As shown, it is possible to separate the power source
section 2 from the light source section 3 in the moveable
ultraviolet irradiation apparatus 1 of the present invention, after
prohibiting the irradiation of ultraviolet light. The separated
light source section 3 is placed on the power source section 2. As
a result, the projected area on the floor (the area of the entire
apparatus, seen from the top as in FIG. 2) can be made smaller, as
compared to conventional moveable ultraviolet irradiation
apparatuses wherein a power source section and a light source
section are difficult to separate. Therefore, it can be transported
on a compact vehicle, such as a delivery van and the like, on which
conventional moveable ultraviolet irradiation apparatuses cannot be
carried.
[0067] By placing a light source section 3 on a power source
section 2, the upper face of the housing 4 of the power source
section 2 can block the opening made in the cover of light source
section 3 for passing the ultraviolet light. As a result, the light
source 9 can be blocked from the outside, thereby preventing the
light source from being stained or getting broken.
[0068] In the case of FIG. 3, the light source section 3 is turned
90 degrees and placed on the power source section 2. The support 12
formed on the upper part in the forward direction of the power
source section 2 supports the portion of the light source section
3, which extruded from the power source section 2. In this state,
for example, a lock 13 is set to fix the light source section 3 on
the power source section 2 which facilitates transport and the
like.
[0069] It is also possible to adhere a vibration resistant rubber
on the periphery of the upper face of the power source section 2.
This has an effect that the vibration transmitted to a light source
9 during the transport of the ultraviolet irradiation apparatus 1,
wherein the light source section 3 is placed on the power source
section 2, can be decreased.
[0070] As described above, the use of a low-pressure mercury lamp
as a light source according to the present invention can solve all
the problems found with conventional ultraviolet irradiation
apparatuses that use a high-pressure mercury lamp alone as a light
source. The conditions of UV irradiation with a low-pressure
mercury lamp may vary depending on the kind of the ultraviolet
curable coating agent (composition), selection of coating
conditions, and thickness of the layer of the ultraviolet curable
coating agent applied to a floor surface. When the light source is
a low-pressure mercury lamp alone, the obtained cured coating film
may contain defects such as Tortoiseshell Pattern, Wrinkle, Fog and
the like, depending on the composition of coating agent, structure
of light source section, irradiation conditions of ultraviolet
light, irradiation site and the like. The present invention is free
of such defects of the film as long as the amount of irradiation is
sufficient, because an ultraviolet curable coating agent is cured
by the irradiation of ultraviolet light having a short wavelength
of about 254 nm, which is derived from a low-pressure mercury lamp
showing a low irradiation amount and low intensity. However, only
the surface and the vicinity of the surface of a coating film is
cured in a relatively short time in the area where ultraviolet
light is not sufficiently irradiated (UV insufficient area). The
extremely thin cured portion shrinks upon curing, thus producing
the defects of the coating film as mentioned above (which of the
above-mentioned Tortoiseshell Pattern, Wrinkle and Fog would occur
depends on various conditions relating to curing and shrinkage).
Particularly, the coating agent away from the light source section
is exposed to an undesired irradiation of ultraviolet light leaking
from the cover of the light source section, where the intensity of
the ultraviolet light is considerably low. In such area (UV
insufficient area), the above-mentioned defects of coating film
tend to occur easily. As a result, the irradiation amount of
ultraviolet light (=intensity of ultraviolet light x irradiation
time) becomes small, which in turn may cause the above-mentioned
defects of coating film, even when the coating agent is directly
under the light source section. The defects of coating film can be
prevented by appropriately setting the various conditions of the
coating agent, moving rate (irradiation rate) of the ultraviolet
irradiation apparatus, re-irradiation and the like However, when
the floor surface to be irradiated is narrow or has a complicated
shape, appropriate operation of ultraviolet irradiation apparatus
according to the above-mentioned setting tends to be difficult.
[0071] The present inventors have further studied the moveable
ultraviolet irradiation apparatus of the present invention. As a
result, they have surprisingly found that, by superposing
ultraviolet light having a long wavelength, which is emitted from a
second light source section having a dominant wavelength of not
less than 320 nm as a light source in addition to the ultraviolet
light having a short wavelength emitted from a low-pressure mercury
lamp, the above-mentioned defects of coating film can be certainly
prevented. As used herein, the radiation source of the ultraviolet
light having a dominant wavelength of not less than 320 nm is a
high-pressure mercury lamp, a metal halide lamp, a black light
(black lamp), a black-blue light (black-blue lamp) and the like.
The black light is a low-pressure mercury lamp (germicidal lamp and
the like), which releases ultraviolet light having a short
wavelength (254 nm), permits change of light emission wavelength
band to 320 nm-400 nm ultraviolet light by adhering a fluorescent
material to the glass surface inside the lamp, and which has a
lower output as compared to general high-pressure mercury lamps.
Hereinafter, high-pressure mercury lamp and black light are used
for further explanation as the examples of the radiation source of
at least these ultraviolet lights having a dominant wavelength of
not less than 320 nm. It is needless to say that the embodiments of
the invention are not limited to these. According to the present
invention ultraviolet light derived from a high-pressure mercury
lamp and/or a black light are/is superposed on the ultraviolet
light derived from a low-pressure mercury lamp, thereby ensuring
that, even if irradiation of the ultraviolet light derived from a
low-pressure mercury lamp is insufficient and a thin cured part is
formed on the surface of a coating film, the ultraviolet light
derived from the high-pressure mercury lamp and/or the black light
are/is irradiated to achieve sufficient curing of the part other
than the surface of the coating film, whereby the defects of
coating film can be surely prevented as mentioned above.
[0072] Therefore, the moveable ultraviolet irradiation apparatus of
the present invention preferably has, in addition to the light
source section of the above-mentioned low-pressure mercury lamp, a
second light source section which is a high-pressure mercury lamp
and/or a black light By this constitution, a moveable ultraviolet
irradiation apparatus can be realized, which provides an advantage
of ensured prevention of occurrence of defects of coating film, in
addition to the aforementioned advantages over conventional
ultraviolet irradiation apparatuses as using a high-pressure
mercury lamp alone as a light source.
[0073] With respect to superposition of the ultraviolet light
derived from a low-pressure mercury lamp and the ultraviolet light
derived from a high-pressure mercury lamp and/or a black light,
when the ultraviolet light derived from a high-pressure mercury
lamp reaches the coating agent earlier than or at the same time as
the ultraviolet light derived from the low-pressure mercury lamp,
the amount of the ultraviolet light derived from the high-pressure
mercury lamp and/or the black light, which is sufficient to cure
the coating agent, makes the cured coating film too stiff, and
causes easy occurrence of cracks and the like, as well as the
defects of cured coating film, such as peeling of coating film from
a floor material and the like. For irradiation of ultraviolet light
to cure ultraviolet curable coating agent applied on a floor
surface, by the use of an ultraviolet irradiation apparatus
equipped with the above-mentioned second light source section, it
is important that ultraviolet light derived from the low-pressure
mercury lamp be first irradiated, and the amount of the ultraviolet
light derived from the high-pressure mercury lamp and/or the black
light be adjusted upon irradiation.
[0074] The second light source section, which comprises a
high-pressure mercury lamp and/or a black light, is subject to no
particular limitation as to the manner of its setting, as long as
the ultraviolet light from the above-mentioned low-pressure mercury
lamp first reaches the ultraviolet curable coating agent and the
ultraviolet light from the high-pressure mercury lamp and/or black
light reaches next.
[0075] FIG. 4 is a simplified side view of a preferable second
embodiment of the moveable ultraviolet irradiation apparatus 21 of
the present invention. FIG. 5 is a top view thereof. the moveable
ultraviolet irradiation apparatus 21 of the embodiment shown in
FIG. 4 and FIG. 5 is the same as the moveable ultraviolet
irradiation apparatus 1 shown in FIG. 1-FIG. 3, except that a
second light source section is further installed, wherein the like
parts are shown with like symbols and explanation is omitted.
[0076] The ultraviolet irradiation apparatus 21 shown in FIG. 4 and
FIG. 5 comprises a high-pressure mercury lamp and a black light 23,
24 on both sides of the light source section 3 and at the upper
side of the low-pressure mercury lamp on the forward end of the
section 3, thereby realizing a second light source section. An
ultraviolet irradiation apparatus comprising a second light source
section consisting of such high-pressure mercury lamp and/or black
light is capable of ensuring that ultraviolet light from the
above-mentioned low-pressure mercury lamp reaches the ultraviolet
curable coating agent first and then ultraviolet light from the
high-pressure mercury lamp and/or black light reaches, thereby
certainly preventing the above-mentioned defects of a coating
film.
[0077] The second light source may be realized with the
high-pressure mercury lamps or black lights 23 alone set on both
sides of the light source section 3 or with high-pressure mercury
lamp or black light 24 alone set at the upper side of the
low-pressure mercury lamp 9. As shown in FIG. 4 and FIG. 5, the
second light source section consisting of high-pressure mercury
lamps or black lights 23, 24 set on both parts is particularly
preferable, because it ensures prevention of the above-mentioned
defects of coating film. Even when there occurs a need to terminate
the irradiation work using the ultraviolet irradiation apparatus on
the way and turn back the apparatus as is, moreover, the coating
agent in front of the light source section can be irradiated with
not only UV light from the low-pressure mercury lamp, but the UV
light from the high-pressure mercury lamp or black light.
Consequently, occurrence of the above-mentioned defects of coating
film can be particularly preferably prevented.
[0078] The above-mentioned second light source section may consist
of a high-pressure mercury lamp or black light disposed in front of
the low-pressure mercury lamp on the forward end of the light
source section, instead of the high-pressure mercury lamp or black
light disposed at the upper side of the low-pressure mercury lamp
on the forward end of the light source section. When a
high-pressure mercury lamp 24 is additionally disposed at the upper
side or in front of the low-pressure mercury lamp 9 on the forward
end of the above-mentioned light source section 3, long wavelength
ultraviolet light may be superposed during the initial stage of the
irradiation of short wavelength ultraviolet light and the
irradiation time of ultraviolet light derived from the
high-pressure mercury lamp and/or black light may be made the same
as or shorter than the irradiation time of the ultraviolet light
derived from the low-pressure mercury lamp.
[0079] When a second light source section comprising a
high-pressure mercury lamp and/or a black light as a light source
is equipped, the kind of the high-pressure mercury lamp and black
light is not particularly limited. FIG. 4 and FIG. 5 show an
example where a high-pressure mercury lamp (H004-L21, IWASAKI
ELECTRIC CO., LTD.) is disposed at the upper side of the
low-pressure mercury lamp and a black-blue lamp (FL15BLB, TOSHIBA)
is disposed on both sides of the light source. In this case, the
high-pressure mercury lamp to be disposed at the upper side or in
front of the low-pressure mercury lamp shows a UV irradiation
intensity of 2 mW/cm.sup.2 (365 nm) as measured with an irradiation
intensity meter (UVP-301G, EYE GRAPHICS Co. Ltd.) on the floor
surface upon irradiation from 43 cm above the floor surface. The UV
irradiation intensity as measured with an irradiation intensity
meter (UVP-301G, EYE GRAPHICS Co. Ltd.) on the floor surface upon
irradiation from 2 cm above the floor surface with a black-blue
lamp disposed on both sides of the light source section is 0.5
mW/cm.sup.2 (365 nm intensity). By setting a black-blue lamp, which
has a weak output as compared to a typical high-pressure mercury
lamp, on both sides as mentioned above, consumption power can be
advantageously reduced.
[0080] The moveable ultraviolet irradiation apparatus of the
present invention may have any structure as long as it comprises a
power source section equipped with wheels, and a light source
section electrically connected to the power source section to emit
ultraviolet light in response to the power supply from the power
source section, and the light source section having a low-pressure
mercury lamp as a light source, and is not limited to the structure
shown in the embodiment of FIG. 1-FIG. 3.
[0081] For example, it may be a handy type ultraviolet irradiation
apparatus comprising a power source section equipped with wheels,
and a light source section electrically connected to the power
source section to emit ultraviolet light in response to the power
supply from the power source section, and the light source section
having a miniaturized low-pressure mercury lamp. In such handy type
UV irradiation, the operator is not restricted by the length of the
electric cord connecting the light source section and the power
source section, but can continue the irradiation work while pulling
the power source section with the light source section in hand,
because a power source section is equipped with a wheel.
[0082] FIG. 6 is a cross section showing a simplified view of the
light source section 31 of a handy type apparatus of the present
invention. For making a handy type apparatus, a light source
(low-pressure mercury lamp 32, high-pressure mercury lamp 33) and a
cover 34 should be made smaller than those in the aforementioned
embodiments. The cover 34 has a holder part 35 on the opposite side
from the opening formed for the passage of the ultraviolet light.
By holding this holder part 35, the operator holds only light
source section 31 of the moveable ultraviolet irradiation apparatus
and proceed with the irradiation work smoothly.
[0083] In the embodiment shown in FIG. 6, a high-pressure mercury
lamp 33 is disposed at the upper part of the low-pressure mercury
lamp 32. In the present invention, the above-mentioned low-pressure
mercury lamp and a high-pressure mercury lamp may be combined in a
handy type apparatus, or the low-pressure mercury lamp alone may be
made a light source for a handy type apparatus.
[0084] The present invention also provides a method for curing a
coating film by irradiation of ultraviolet light on a specific
ultraviolet curable coating agent using the above-mentioned
ultraviolet irradiation apparatus wherein a light source consists
of a low-pressure mercury lamp. According to this method, the
target to form a cured coating film on is not limited to floor
materials.
[0085] 2. Ultraviolet Curable Coating Agent
[0086] The ultraviolet curable coating agent in the present
invention contains, as a required component, a photopolymerizable
resin and a photopolymerization initiator. After applying the
coating agent to a substrate, it is exposed to UV light, thereby
forming a cured coating film on the surface of the substrate. The
ultraviolet curable coating agent of the present invention is a
coating film material capable of protecting the surface of a
substrate or affording good appearance. For example, it can be used
as paints, polish, wax, surface treatment agent and the like.
[0087] The photopolymerizable resin and a photopolymerization
initiator are explained in the following.
[0088] The present inventors have considered using, as a light
source of an ultraviolet irradiation apparatus, a low-pressure
mercury lamp seldom used for forming a cured coating film so far,
in view of the insufficient curing of a coating film achieved
thereby and a longer curing time required as compared to the use of
a high-pressure mercury lamp as a light source, and found the
above-mentioned ultraviolet irradiation apparatus capable of curing
an ultraviolet curable coating agent. Furthermore, the present
inventors have studied ultraviolet curable coating agents suitable
for the ultraviolet irradiation apparatus of the present invention,
which is capable of forming, even by the use of a low-pressure
mercury lamp as a light source, a cured coating film having similar
properties (e.g., stain resistance, adhesion to substrate and the
like) to those achieved by the use of a high-pressure mercury lamp,
and which requires a shorter curing time per unit area of the
coating film than by the use of a high-pressure mercury lamp (100 V
type). As a result, they have found that an ultraviolet curable
coating agent containing a photopolymerizable resin containing a
urethane(meth)acrylate resin is extremely suitable for curing by
the use of the above-mentioned ultraviolet irradiation apparatus
including a low-pressure mercury lamp as a light source.
[0089] In the following, an ultraviolet curable coating agent
containing a photopolymerizable resin containing a
urethane(meth)acrylate resin is explained, but the ultraviolet
curable coating agent to be cured using an ultraviolet irradiation
apparatus of the present invention is not limited to the
following.
[0090] 2-1. Photopolymerizable Resin
[0091] The photopolymerizable resin in the present invention cures
by being exposing to light having a wavelength of 200-800 nm, and
preferably contains a urethane(meth)acrylate resin. The
urethane(meth)acrylate resin is contained in a proportion of not
less than 10 wt %, preferably not less than 50 wt %, of the entire
photopolymerizable resin. The photopolymerizable resin in the
present invention may contain a resin other than
urethane(meth)acrylate resin, as long as the object of the present
application is not impaired.
[0092] As the rosin other than urethane(meth)acrylate resin, for
example, unsaturated polyester resin, epoxy(meth)acrylate resin and
the like are mentioned, 1 or more of which may be contained.
[0093] As the unsaturated polyester resin in the present invention,
for example, acrylate synthesized by the reaction of phthalic
anhydride, propylene oxide and acrylic acid; acrylate synthesized
by the reaction of adipic acid, 1,6-hexanediol and acrylic acid;
acrylate synthesized by the reaction of trimellitic acid,
diethylene glycol and acrylic acid; unsaturated polyester
consisting of 1,2-propylene glycol, phthalic anhydride and maleic
anhydride; unsaturated polyester containing allyl group-containing
compound such as trimethylolpropane diallyl ether (TMPDA),
trimethylolpropane triallyl ether (TMPTAE), triallyl isocyanate,
diallyl phthalate and the like and styrene; and the like are
mentioned.
[0094] The epoxy(meth)acrylate resin to be used in the present
invention is, for example, epoxy acrylate (bisphenol A type)
synthesized by the reaction of bisphenol A, epichlorohydrin and
acrylic acid, epoxy acrylate (bisphenol S type) synthesized by the
reaction of bisphenol S, epichlorohydrin and acrylic acid, epoxy
acrylate (bisphenol F type) synthesized by the reaction of
bisphenol F, epichlorohydrin and acrylic acid, epoxy acrylate
(phenol novolak type) synthesized by the reaction of phenol
novolak, epichlorohydrin and acrylic acid, and the like.
[0095] The urethane(meth)acrylate resin in the present invention is
a resin containing at least one each of (meth)acryloyl
group(CH.sub.2.dbd.CHC(O)-- or CH.sub.2.dbd.C(CH.sub.3)C(O)--) and
a urethane bond in a molecule, wherein (meth)acryloyl group and
urethane bond may be contained in any ratio. The
urethane(meth)acrylate resin of the present invention can be
generally produced by a method similar to the production of
urethane(meth)acrylate. The urethane(meth)acrylate obtained by, for
example, (1) urethane reaction of an isocyanate compound and a
hydroxyl compound having a (meth)acryloyl group in a molecule, (2)
urethane reaction of an isocyanate compound having a (meth)acryloyl
group in a molecule and a hydroxyl compound, and the like.
[0096] The urethane reaction is generally carried out using dibutyl
tin dilaurate (DBTDL) as a catalyst. However, when the present
inventors conducted the urethane reaction using an aluminum
compound instead of DBTDL, a highly viscous urethane(meth)acrylate
resin could be produced, and when ultraviolet light was irradiated
to a coating film containing an ultraviolet curable coating agent
produced using this, a superior effect of suppression of occurrence
of Tortoiseshell Pattern, Wrinkle, Fog and the like found in the
boundary between a UV irradiation area and a UV insufficient area
and the like could be afforded. While heavy metals such as DBTDL
and the like may cause an adverse influence on the environment and
human body, by substituting the metal to an aluminum compound,
heavy metal that adversely affects the environment and human body
can be preferably eliminated.
[0097] The urethane(meth)acrylate resin obtained by reacting an
isocyanate compound and a hydroxyl compound using an aluminum
compound as a catalyst is novel and has the above-mentioned
superior properties and is useful as a photopolymerizable resin for
an ultraviolet curable coating agent.
[0098] The preferable aluminum compound in the present invention is
aluminum.
[0099] As the above-mentioned isocyanate compound, there are
mentioned a monoisocyanate compound, a diisocyanate compound, a
polyisocyanate compound and the like, which is preferably a
polyisocyanate compound.
[0100] The monoisocyanate compound in the present invention is
exemplified by an aliphatic monoisocyanate compound, an alicyclic
monoisocyanate compound, an aromatic monoisocyanate compound and
the like, which is preferably an aliphatic monoisocyanate
compound.
[0101] The aliphatic moiety of the aliphatic monoisocyanate
compound in the present invention is a linear or branched chain
saturated hydrocarbon group having preferably 1-36, more preferably
6-16, carbon atoms. Examples of the aliphatic monoisocyanate
compound include methyl isocyanate, ethyl isocyanate, n-hexyl
isocyanate, 2-ethylhexyl isocyanate, n-heptyl isocyanate, octyl
isocyanate, nonyl isocyanate, decyl isocyanate, undecyl isocyanate,
dodecyl isocyanate, tridecyl isocyanate, tetradecyl isocyanate,
pentadecyl isocyanate, hexadecyl isocyanate, icosyl isocyanate,
triacontyl isocyanate and the like, with preference given to
n-hexyl isocyanate.
[0102] The alicyclic moiety of the alicyclic monoisocyanate
compound in the present invention is saturated alicyclic
hydrocarbon group having preferably 3-20, more preferably 6-10,
carbon atoms. The alicyclic moiety is optionally substituted by one
or more substituents as long as the substitution does not impair
the object of the present invention. Examples of the substituent
include isophoronyl, cyclohexyl and the like. Examples of the
alicyclic monoisocyanate compound include cyclopropyl isocyanate,
cyclobutyl isocyanate, cyclopentyl isocyanate, cyclohexyl
isocyanate, cycloheptyl isocyanate, cyclooctyl isocyanate and the
like, with preference given to cyclohexyl isocyanate.
[0103] The aromatic moiety of the aromatic monoisocyanate compound
in the present invention is preferably benzene, naphthalene and the
like, more preferably benzene. Two or more aromatic moieties may be
included, wherein they are bonded via linear or branched chain
alkylene preferably having 1-10 carbon atoms (particularly
preferably methylene). The aromatic moiety is optionally
substituted by one or more substituents as long as the substitution
does not impair the object of the present invention. Examples of
the substituent include linear or branched chain alkyl having
preferably 6-20, more preferably 6-12, carbon atoms, alkylene
having preferably 1-26, more preferably 1-12, carbon atoms, and the
like. Examples of the aromatic monoisocyanate compound include
phenyl isocyanate, naphthalene isocyanate, hexylphenyl isocyanate,
heptylphenyl isocyanate, octylphenyl isocyanate, nonylphenyl
isocyanate, decylphenyl isocyanate, undecylphenyl isocyanate,
dodecylphenyl isocyanate, benzyl isocyanate, phenetyl isocyanate,
4,4'-diphenylmethylene isocyanate and the like, with preference
given to benzyl isocyanate.
[0104] The diisocyanate compound in the present invention may be,
for example, an aliphatic diisocyanate compound, an alicyclic
diisocyanate compound, an aromatic diisocyanate compound and the
like, with preference given to aliphatic diisocyanate.
[0105] The aliphatic moiety of the aliphatic diisocyanate compound
in the present invention is linear or branched chain saturated
hydrocarbon group having preferably 1-20, more preferably 6-10,
carbon atoms. The aliphatic moiety is optionally substituted by one
or more substituents as long as the substitution does not impair
the object of the present invention. Examples of the substituent
include mono or polyvalent group derived from isophorone,
methylenebis(cyclohexane) and the like, carboxyl group and the
like. Examples of the aliphatic diisocyanate compound include
trimethylene dilsocyanate, tetramethylene diisocyanate,
hexamethylene diisocyanate, pentamethylene diisocyanate,
1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene
diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or
2,2,4-trimethylhexamethylene diisocyanate,
2,6-bis(isocyanatomethyl)hexanoic acid and the like, with
preference given to hexamethylene diisocyanate.
[0106] The alicyclic moiety of the alicyclic diisocyanate compound
in the present invention is saturated or unsaturated alicyclic
hydrocarbon group having preferably 3-20, more preferably 6-10,
carbon atoms. Two or more unsaturated alicyclic hydrocarbon groups
may be present, in which case they are bonded via linear or
branched chain alkylene having preferably 1-12, more preferably
6-10, carbon atoms. The alicyclic moiety is optionally substituted
by one or more substituents as long as the substitution does not
impair the object of the present invention. Examples of the
substituent include linear or branched chain alkyl, having
preferably 4-12, more preferably 6-10, carbon atoms and the like.
Examples of the alicyclic diisocyanate compound include
1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate,
1,3-cyclohexane diisocyanate,
1,3-bis(isocyanatomethyl)-3,3,5-trimethylcyclohexane,
4,4'-methylenebis(cyclohexyl isocyanate), 2,4-cyclohexane
diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane,
1,4-bis(isocyanatomethyl)cyclohexan- e, and the like, with
preference given to 1,4-cyclohexane diisocyanate.
[0107] The aromatic moiety of aromatic diisocyanate compound in the
present invention is preferably benzene or naphthalene, more
preferably naphthalene. Two or more aromatic rings may be included,
wherein each is bonded via a single bond, linear or branched chain
alkylene having preferably 1-20, more preferably 6-12, carbon atoms
or an oxygen atom and the like. The aromatic moiety is optionally
substituted by one or more substituents as long as the object of
the present invention is not impaired. Examples of the substituent
include linear or branched chain alkyl having preferably 2-20, more
preferably 6-12, carbon atoms, amino and the like. Examples of
aromatic diisocyanate compound include m-phenylene diisocyanate,
p-phenylene diisocyanate, 4,4'-biphenyl diisocyanate,
1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate,
2,4- or 2,6-tolylene diisocyanate, 4,4'-diphenyl ether
diisocyanate, isophorone diisocyanate, 1,6-hexane diisocyanate;
1,3- or 1,4-xylylene diisocyanate, a mixture of 1,3-xylylene
diisocyanate and 1,4-xylylene diisocyanate,
.omega.,.omega.'-diisocyanato-1,4-diethylbenze- ne, 1,3- or
1,4-bis(1-isocyanato-1-methylethyl)benzene and a mixture of
1,3-bis(1-isocyanato-1-methylethyl)benzene and
1,4-bis(1-isocyanato-1-met- hylethyl)benzene and the like, with
preference given to 4,4'-diphenylmethane diisocyanate and
1,6-hexane diisocyanate.
[0108] The polyisocyanate compound in the present invention may be,
for example, aliphatic polyisocyanate compound, alicyclic
polyisocyanate compound, aromatic polyisocyanate compound and the
like, with preference given to aliphatic polyisocyanate. of the
polyisocyanate compounds, one having not less than 3 isocyanato
groups is particularly preferable.
[0109] The aliphatic moiety of aliphatic polyisocyanate compound in
the present invention is linear or branched chain saturated
hydrocarbon group having preferably 1-20, more preferably 6-10,
carbon atoms, which is optionally substituted by one or more
substituents as long as the object of the present invention is not
impaired. Examples of the substituent include monovalent or
polyvalent groups derived from isophorone, cyclohexane and the
like. Examples of aliphatic polyisocyanate compound include
1,4,8-triisocyanatooctane, 1,6,11-triisocyanatoundecane,
1,8-diisocyanato-4-isocyanatomethyloctane,
1,3,6-triisocyanatohexane,
2,5,7-trimethyl-1,8-diisocyanato-5-isocyanatomethyloctane and the
like.
[0110] The alicyclic moiety of alicyclic polyisocyanate compound in
the present invention is saturated alicyclic hydrocarbon group
having preferably 3-20, more preferably 3-10, carbon atoms, wherein
two or more saturated alicyclic hydrocarbons may form a fused ring.
Alternatively, two or more alicyclic hydrocarbon groups may be
bonded to each other via single bond or a methylene group. The
alicyclic moiety is optionally substituted by one or more
substituents as long as the object of the present invention is not
impaired. Examples of the substituent include linear or branched
chain alkyl having preferably 4-12, more preferably 6-10, carbon
atoms, linear or branched chain alkylene having preferably 4-12
carbon atoms, and the like. Examples of alicyclic polyisocyanate
compound include
[0111] 1,3,5-triisocyanatocyclohexane,
[0112] 1,3,5-tris(isocyanatomethyl)cyclohexane,
[0113]
2-(3-isocyanatopropyl)-2,5-di(isocyanatomethyl)bicyclo-[2.2.1]hepta-
ne,
[0114]
2-(3-isocyanatopropyl)-2,6-di(isocyanatomethyl)bicyclo-[2.2.1]hepta-
ne,
[0115]
3-(3-isocyanatopropyl)-2,5-di(isocyanatomethyl)bicyclo-[2.2.1]hepta-
ne,
[0116]
5-(2-isocyanatoethyl)-2-(isocyanatomethyl)-3-(3-isocyanatopropyl)bi-
cyclo[2.2.1]heptane,
[0117]
6-(2-isocyanatoethyl)-2-(isocyanatomethyl)-3-(3-isocyanatopropyl)bi-
cyclo[2.2.1]heptane,
[0118]
5-(2-isocyanatoethyl)-2-(isocyanatomethyl)-2-(3-isocyanatopropyl)bi-
cyclo[2.2.1]heptane,
[0119]
6-(2-isocyanatoethyl)-2-(isocyanatomethyl)-2-(3-isocyanatopropyl)bi-
cyclo[2.2.1]heptane and the like, with preference given to
1,3,5-tris(isocyanatomethyl cyclohexane.
[0120] The aromatic moiety of aromatic polyisocyanate compound in
the present invention is preferably benzene, naphthalene and the
like, more preferably naphthalene, wherein two or more of aromatic
rings may be included. In this case, each ring may be bonded via a
single bond, linear or branched chain alkylene having preferably
2-20, more preferably 6-12, carbon atoms, and the like. The
aromatic moiety is optionally substituted by one or more
substituents as long as the object of the present invention is not
impaired. Examples of the substituent include linear or branched
chain alkyl having preferably 2-20, more preferably 6-12, carbon
atoms, linear or branched chain alkylene having preferably 2-20
carbon atoms, and the like. Examples of aromatic polyisocyanate
compound include
1,3-bis(.alpha.,.alpha.-dimethylisocyanatomethyl)benzene,
triphenylmethane-4,4",4"-triisocyanate, 1,3,5-triisocyanatobenzene,
2,4,6-triisocyanatotoluene,
4,4'-diphenylmethane-2,2',5,5'-tetraisocyanat- e and the like;
1,3,5-triisocyanatomethylbenzene and the like, with preference
given to 1,3-bis(.alpha.,.alpha.-dimethylisocyanatomethyl)benz-
ene.
[0121] The unsaturated urethane(meth)acrylate resin compound of the
present invention can contain one or more of the above-mentioned
isocyanate compounds in combination. Further, biuret compounds,
isocyanurate compounds, adducts obtained by urethane reaction of
various polyhydroxy compounds, allophanate compounds,
oxadiazinetrione compounds and uretidione compound, which are the
denatured compounds from one or more of the above-mentioned
isocyanate compound, can be used as the isocyanate compound in the
present invention. Of these, isocyanurate compounds are
particularly preferable, such as tris(isocyanatoalkyl) -substituted
isocyanurate compound. The alkyl moiety of
tris(isocyanatoalkyl)-substituted isocyanurate compound includes
linear or branched chain alkyl having 2-20, preferably 2-10, carbon
atoms, such as ethyl, butyl, hexyl and the like. Particularly
preferable tris(isocyanatoalkyl)-substituted isocyanurate compound
is tris(6-isocyanatohexyl) isocyanurate.
[0122] Examples of hydroxyl compound having a (meth)acryloyl group
in a molecule in the present invention include hydroxyalkyl
(meth)acrylate, hydroxycycloalkyl (meth)acrylate, polyalkylene
glycol mono(meth)acrylate, adduct of glycidyl (meth)acrylate and
(meth)acrylic acid, ring-opening reaction product of these
(meth)acrylate compounds and .epsilon.-caprolactone, adduct of
glycidyl ether and (meth)acrylic acid, adduct of phenyl glycidyl
ether and (meth)acrylic acid and the like, with preference given to
hydroxyalkyl (meth)acrylate and polyalkylene glycol
mono(meth)acrylate. The hydroxyl compounds having (meth)acryloyl in
a molecule can be used alone or in combination of two or more of
these.
[0123] The alkyl moiety of hydroxyalkyl (meth)acrylate in the
present invention is linear or branched chain alkyl having
preferably 2-100, more preferably 2-60, carbon atoms, which is
optionally substituted as long as the object of the present
invention is not impaired. Examples of the substituent include
phenoxy, groups derived from caprolactam denatured diol, and the
like. The hydroxyalkyl (meth)acrylate may contain one or more
(meth)acryloyl groups in a molecule. Examples of hydroxyalkyl
(meth)acrylate include mono(meth)acrylate such as 2-hydroxyethyl
(meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl
(meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl
(meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate and the
like; di(meth)acrylate such as trimethylolpropane di(meth)acrylate,
trimethylolethane di(meth)acrylate, glycidol dimethacrylate and the
like; pentaerythritol tri(meth)acrylate, dipentaerythritol
hexa(meth)acrylate and the like, with preference given to
pentaerythritol tri(meth)acrylate.
[0124] The cycloalkyl moiety of hydroxycycloalkyl (meth)acrylate in
the present invention is cycloalkyl having preferably 3-30, more
preferably 4-20, carbon atoms, which is optionally substituted as
long as the object of the present invention is not impaired.
Examples of the substituent include methyl, ethyl, and a group
derived from ethoxylated bisphenol. The hydroxycycloalkyl
(meth)acrylate may contain one or more (meth)acryloyl groups in a
molecule. Examples of hydroxycycloalkyl (meth)acrylate include
cyclohexanedimethanol mono(meth)acrylate, cycloheptanedimethanol
mono(meth)acrylate, cyclooctanedimethanol mono(meth)acrylate,
caprolactam denatured mono(meth)acrylate, spiroglycol denatured
mono(meth)acrylate and the like, with preference given to
cyclohexanedimethanol mono (meth) acrylate.
[0125] The alkyl moiety of polyalkylene glycol mono(meth)acrylate
in the present invention is linear or branched chain alkyl having
1-100, preferably 2-60, carbon atoms, wherein each alkyl moiety may
be bonded via an oxygen atom. The polyalkylene glycol
mono(meth)acrylate may contain one or more (meth)acryloyl groups in
a molecule. Examples of polyalkylene glycol mono(meth)acrylate
include mono(meth)acrylate such as polyethylene glycol mono(meth)
acrylate, polypropylene glycol mono(meth ) acrylate,
poly(tetramethyleneoxido mono(meth)acrylate) and the like, and
adduct of (meth)acrylic acid and ethylene-propylene glycol block
polymer, with preference given to polyethylene glycol
mono(meth)acrylate.
[0126] It is also possible to concurrently use various
polyhydroxyl-containing compounds in urethane reaction of
isocyanate compound and a hydroxyl compound having a (meth)acryloyl
group in a molecule. The use of a polyhydroxyl-containing compound
is preferable because it improves water dispersibility and water
emulsifiability of the coating composition, and suppresses the warp
of the coating object (floor, floor material, plastic film and the
like). The polyhydroxyl-containing compound can be used for the
production method of the urethane(meth)acrylate resin as in the
following. First, the polyhydroxyl-containing compound is
preliminarily reacted with an excess isocyanate compound to
synthesize a prepolymer having an isocyanate terminal. Then, this
prepolymer is reacted with a hydroxyl compound having a
(meth)acryloyl group in a molecule to produce the
urethane(meth)acrylate resin. These reactions can be carried out
concurrently.
[0127] Examples of the polyhydroxyl-containing compound include
alkylene glycol, polyhydroxyl-containing carboxylic acid and
derivatives thereof (e.g., hydroxypivalic acid neopentyl glycol
ester, dimethylolpropionic acid, dimethylolbutanoic acid and the
like), polyhydroxyl-containing alicyclic compound (e.g.,
cyclohexanedimethylol, 1,4-cyclohexanediol, spiroglycol (e.g.,
3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxa-
spiro[5.5]undecane and the like),
tricyclo[5.2.1.0]decane-4,8-dimethanol,
2,2,6,6-tetramethylolcyclohexanol-1, inositol and the like),
bisphenol compound and adduct of alkylene oxide and bisphenol
compound (e.g., hydrogenated bisphenol A, adduct of ethylene oxide
and bisphenol A, adduct of propylene oxide and bisphenol A, adduct
of hydroxyethylene oxide and bisphenol A, adduct of ethoxy and
bisphenol S and the like), polyhydroxyl-containing aliphatic
compound (e.g., trimethylolethane, trimethylolpropane,
ditrimethylolethane, ditrimethylolpropane, glycerin, diglycerol,
3-methylpentane-1,3,5-triol, pentaerythritol, dipentaerythritol,
tripentaerythritol, mannitol, sorbitol and the like), isocyanurate
compound (e.g., tris(2-hydroxyethyl)isocyanurate and the like),
glucose (e.g., hydroxypropylmethylcellulose phthalate,
hydroxypropylmethylcellulose acetate and the like); polyester
polyol, polyether polyol, polycarbonate polyol (preferably
polyester polyol) and the like, particularly preferably
dipentaerythritol. These can be used alone or in combination of two
or more compounds thereof.
[0128] The alkylene moiety of alkylene glycol of the
above-mentioned polyhydroxyl-containing compound is linear or
branched chain alkylene having 2-100, preferably 2-60, carbon
atoms, which is optionally substituted by one or more substituents,
such as halogen atom, --SH, --SR (wherein R is alkyl which is
preferably alkyl having 2-12 carbon atoms) and the like. Examples
of alkylene glycol include ethylene glycol, 1,3-propylene glycol,
1,2-propylene glycol, diethylene glycol, dipropylene glycol,
neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol,
1,9-nonanediol, 1,10-decanediol, 2,2,4-trimethyl-1,3-pent- anediol,
3-methyl-1,5-pentanediol, dichloroneopentyl glycol,
dibromoneopentyl glycol and the like, with preference given to
ethylene glycol and dipropylene glycol.
[0129] An aliphatic and/or alicyclic urethane(meth)acrylate resin
obtained by the above-mentioned method, which shows less
discoloring is preferable for floors.
[0130] 2-2. Photopolymerization Initiator
[0131] The photopolymerization initiator is not subject to any
particularly limitation as long as it absorbs light and produces
radical or cation, with preference given to one that strongly
absorbs ultraviolet light having a wavelength that a low-pressure
mercury lamp releases It may be used in combination with a
generally known photosensitizer that absorbs ultraviolet light near
254 nm.
[0132] As the photopolymerization initiator, for example, benzoyl
(e.g., 1-hydroxycyclohexylphenylketone,
2-methyl-1-[4-(methylthio)phenyl]-2-morp- holinopropane-1-one,
2-hydroxy-2-methyl-1-phenylpropane-1-one,
2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butane-1-one,
1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane-1-one,
1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one,
4'-isopropyl-2-hydroxy-2-methylpropiophenone and the like),
phosphine oxide (e.g., bisacylphosphine oxide, acylphosphine oxide,
2,4,6-trimethylbenzoyldiphenylphosphine oxide,
2,6-dimethylbenzoyldipheny- lphosphine oxide,
benzoyldiethoxyphosphine oxide, bis(2,6-dimethoxybenzoyl-
)-2,4,4-trimethylpentylphosphine oxide and the like), benzoin
(e.g., benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl
ether, benzoin isobutyl ether, n-butyl benzoin ether and the like),
acetophenone (e.g., p-tert-butyltrichloroacetophenone,
p-tert-butyldichloroacetophenon- e, acetophenone,
2,2-diethoxyacetophenone, chlorinated acetophenone,
hydroxyacetophenone, .alpha.,.alpha.-dichloro-4-phenoxyacetophenone
and the like), benzophenone (e.g., benzophenone,
4,4'-dichlorobenzophenone, 4,4'-bis(dimethylamino) benzophenone,
4,4'-bis(diethylamino)-benzophenone- ,
3,3',4,4'-tetra(tert-butylperoxycarbonyl)-benzophenone,
3,3'-dimethyl-4-methoxybenzophenone and the like), thioxanthone
(e.g. 2-chloro-thioxanthone, 2-methyl-thioxanthone,
2,4-diethyl-thioxanthone, 2,4-diisopropyl-thioxanthone and the
like), anthraquinone (e.g., anthraquinone, 2-ethylanthraquinone,
.alpha.-chloroanthraquinone, 2-tert-butylanthraquinone and the
like), benzyl (e.g., benzyl, 4,4'-dimethoxybenzil,
4,4'-dichlorobenzil and the like), benzoic acid ester (e.g., methyl
o-benzoylbenzoate, methyl p-dimethylaminobenzoate and the like),
diketone (e.g., biacetyl, methyl phenylglyoxylate, methyl
benzoylformate and the like), ketal (e.g., benzyl dimethyl ketal,
acetophenone diethyl ketal and the like), dibenzocycloalkanone
(e.g., 10-butyl-2-chloroacridone, dibenzosuberon and the like),
acyl oxime ester, camphorquinone, 3-ketocumarin, tetramethyl
thiuram disulfide, .alpha.,.alpha.'-azobisisobutyronitrile,
benzoylperoxide,
2,2'-bis(o-chlorophenyl)-4,5,4',5'-tetraphenyl-1,2'-biimidazole,
acenaphthene, benzal acetone and the like are included.
[0133] The amount of the photopolymerization initiator to be used
in the present invention is generally 0.01-20 wt %, preferably
0.1-10 wt %, of the photopolymerizable resin. 2-3. Other
components
[0134] The ultraviolet curable coating agent of the present
invention may contain generally known reactive diluent other than
the required component.
[0135] The above-mentioned reactive diluent includes a reactive
diluent having one unsaturated bond, a reactive diluent having two
unsaturated bonds, a reactive diluent having not less than 3
unsaturated bonds and the like. These reactive diluents can be used
alone or in combination of plural kinds thereof.
[0136] The amount of the reactive diluent to be used is generally
preferably not more than 400 parts by weight, more preferably not
more than 100 parts by weight, per 100 parts by weight of the
photopolymerizable resin. When the concentration of the reactive
diluent exceeds 400 parts by weight, the stain resistance, abrasion
resistance, chemical resistance and weatherability of the cured
coating film may be degraded.
[0137] As the reactive diluent having one unsaturated bond, for
example, (meth)acrylic acid, alkyl (meth)acrylate,
dialkylaminoalkyl (meth)acrylate, glycidyl (meth)acrylate, carbitol
(meth)acrylate, isobornyl (meth)acrylate, acryloyl morpholine and
the like are mentioned.
[0138] The alkyl moiety of the above-mentioned alkyl (meth)acrylate
is linear or branched alkyl preferably having 1-20, more preferably
2-10, carbon atoms, which is optionally substituted by one or more
such as hydroxy group, phenoxy group, glycidyl group, carboxyl
group and the like. As alkyl (meth)acrylate, for example, methyl
(meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hexyl
(meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl
(meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl
(meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate and the
like are mentioned, with preference given to 2-hydroxyethyl
(meth)acrylate.
[0139] The alkyl moiety of the above-mentioned dialkylaminoalkyl
(meth)acrylate is linear or branched alkyl preferably having 1-20,
more preferably 2-8, carbon atoms. The alkyl of the dialkyl moiety
are the same or different and each is independently linear or
branched alkyl preferably having 1-20, more preferably 2-8, carbon
atoms. Examples of dialkylaminoalkyl (meth)acrylate include
N,N-dimethylaminoethyl (meth) acrylate, N,N-diethylaminoethyl
(meth)acrylate and the like, with preference given to
N,N-diethylaminoethyl (meth ) acrylate.
[0140] As the reactive diluent having two unsaturated bonds, for
example, alkanediol di(meth)acrylate, polyalkylene glycol
di(meth)acrylate and the like are mentioned.
[0141] The alkane moiety of the above-mentioned alkanediol
di(meth)acrylate is linear, branched or cyclic hydrocarbon
preferably having 1-20, more preferably 2-8, carbon atoms, which is
optionally substituted by one or more of hydroxy group and phenoxy
group. Examples of alkanediol di(meth)acrylate include
1,6-hexanediol di(meth)acrylate, neopentylglycol di(meth)acrylate,
ethylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate,
pentaerythritol di(meth)acrylate and 1,4-butanediol
di(meth)acrylate.
[0142] The alkylene of the above-mentioned polyalkylene glycol
di(meth)acrylate is linear or branched alkylene preferably having
1-20, more preferably 2-10, carbon atoms. Examples of polyalkylene
glycol di(meth)acrylate include polyethylene glycol
di(meth)acrylate, polypropylene glycol di(meth)acrylate,
caprolactam denatured di(meth)acrylate and the like, with
preference given to polyethylene glycol di(meth)acrylate.
[0143] The reactive diluent having 3 or more unsaturated bonds
include, for example, trimethylolpropane tri(meth)acrylate,
pentaerythritol tri(meth)acrylate, dipentaerythritol
hexa(meth)acrylate, tetramethylolmethane tetra(meth)acrylate,
acrylic acid ester of
N,N,N',N'-tetrakis(.beta.-hydroxyethyl)-ethyldiamine and the
like.
[0144] The reactive diluent when the unsaturated bond of the
unsaturated urethane compound is derived from allyl group is
exemplified by diallyl phthalate, diallyl isophthalate, diallyl
adipate and the like.
[0145] The reactive diluent when the unsaturated bond of
unsaturated urethane compound is derived from vinyl group includes,
for example, styrene, acrylonitrile, vinyl acetate, vinyltoluene,
N-vinylpyrrolidone and the like.
[0146] The ultraviolet curable coating agent in the present
invention may contain generally used additives as long as the
object of the present invention is not impaired. For example,
coloring agent, pigment, flat agent, anti-forming agent, deforming
agent, wetting agent, leveling agent, antistatic agent, viscosity
controlling agent, storing stabilizer, antibacterial agent,
preservative, antislip agent, coating film crack inhibitor,
adhesion promoter, dispersant, surfactant, extender pigment, mold
release agent, silane coupling agent, stabilizer, fire retardant
and the like can be used.
[0147] 3. Substrate
[0148] The substrate in the present invention is not particularly
limited and exemplified by vinyl chloride material, polyester
decorative laminate, melamine decorative laminate, wood, stone,
ceramic, plastic, metal, paper, cloth and the like.
[0149] 4. Primer
[0150] The ultraviolet curable coating agent in the present
invention may be directly applied to a substrate, or applied on a
primer layer after coating a suitable primer on a substrate. When
cured with an ultraviolet irradiation apparatus of the present
invention wherein the light source is a low-pressure mercury lamp,
the latter shows superior adhesiveness between substrate and
coating film after curing. It is therefore more preferable to apply
an ultraviolet curable coating agent after applying a primer to a
substrate than to directly apply the ultraviolet curable coating
agent to a substrate.
[0151] The primer layer in the present invention is formed between
an ultraviolet curable coating agent layer and a substrate for
various objects, and the kind of the primer is appropriately varied
depending on the object. For example, for enhanced adhesiveness
between an ultraviolet curable coating agent and a substrate, for
inhibition of permeation of an ultraviolet curable coating agent
through a substrate and for protection of a substrate, a primer
layer is formed. A primer having the necessary property is applied
in a suitable amount to a substrate. The primer layer may include
as many layers as desired, which is preferably 1 or 2 layers in
view of the work efficiency.
[0152] The primer in the present invention is not particularly
limited, as long as it does not impair the object of the prevent
invention. For example, natural and synthetic polymers are
mentioned, such as polyurethane resin, acryl resin, unsaturated
polyester resin, epoxy resin, acrylsilicone resin, fluorine
contained resin, alkyd resin, urea resin, melamine resin, acetic
acid vinyl resin, cellulose resin (e.g., nitrocellulose, cellulose
acetate butyrate and the like), fats and oil (e.g., rosin
derivative, linseed oil, tung oil, soybean oil, castor oil and the
like) and the like. Because light irradiation does not easily cause
discoloration or degradation, polyurethane resin and acryl resin
are preferable.
[0153] The primer of the present invention may contain generally
used additives as long as the object of the present invention is
not impaired. For example, sensitizing agent, coloring agent,
anti-forming agent, deforming agent, wetting agent, leveling agent,
antistatic agent, viscosity controlling agent, storing stabilizer,
antibacterial agent, preservative, antislip agent, coating film
crack inhibitor, adhesion promoter, dispersant, surfactant,
extender pigment, mold release agent, silane coupling agent,
stabilizer, fire retardant and the like are included, which can be
used alone or in combination of two or more thereof.
[0154] The primer of the present invention can take various forms
such as organic solvent form (e.g., organic solvent such as ethyl
acetate, butyl acetate, methanol, ethanol, isopropyl alcohol,
mineral spirit and the like), non-solvent form, aqueous form (use
water as solvent, for example, aqueous solution, aqueous emulsion,
aqueous dispersion and the like). In the case of aqueous form,
solvent evaporation does not produce odor or toxic gas during
drying and is preferable environmentally and for the health of
painter. In addition, since an organic solvent for washing is not
necessary, aqueous form is preferable for worksite application. A
primer in an aqueous form generally has low viscosity and is
suitable for a simple and easy coating method using brush, roller,
mouton, mop, spraying and the like.
[0155] 5. Method of Forming Cured Coating Film
[0156] The cured coating film of the present invention can be
formed as follows.
[0157] The above-mentioned ultraviolet curable coating agent
(preferably ultraviolet curable coating agent containing
photopolymerizable resin containing urethane(meth)acrylate resin)
is applied to a substrate and, using the ultraviolet irradiation
apparatus of the present invention, exposed to ultraviolet light to
cure the coating film, whereby a cured coating film can be formed.
Where necessary, a primer can be applied before coating of a
substrate with an ultraviolet curable coating agent.
[0158] The ultraviolet curable coating agent of the present
invention can be applied to a substrate without using a solvent.
For appropriate application, however, an organic solvent, water and
the like may be added. Examples of the organic solvent include
aromatic solvent such as xylene and toluene, ester solvent such as
ethyl acetate and butyl acetate, alcohol solvent such as methanol
and ethanol and the like. When water is used as a solvent,
application form is not limited, and, for example, emulsion,
molecular dispersion, dispersion and the like can be mentioned.
Considering the health of the worker and burden on the environment,
the use of water as a solvent is preferable.
[0159] The ultraviolet curable coating agent is applied to make the
lower limit of the film thickness after curing by UV irradiation
preferably not less than 4 .mu.m, more preferably not less than 7
.mu.m, and the upper limit of the film thickness after curing by UV
irradiation less than 75 .mu.m, preferably not more than 70 .mu.m
by a generally known method. When the film thickness after curing
is less than 4 .mu.m, the desired gloss of the cured coating film
is not achieved. A film thickness of not less than 75 .mu.m is not
preferable, because sufficient curing takes too long, necessitating
slow move of the ultraviolet irradiation apparatus and causing poor
workability. In this case, cure-shrinkage of the aforementioned
coating agent easily causes warp, breaking and the like of the
substrate forming the cured coating film.
[0160] The ultraviolet curable coating agent can be applied to a
substrate by a known method. For example, air-spray, airless-spray,
brush, roller and the like can be employed.
[0161] The primer of the present invention can be applied to a
substrate by a method similar to the method employed for
application of the above-mentioned ultraviolet curable coating
agent to a substrate.
[0162] The ultraviolet curable coating agent can be applied to a
primer layer by a method similar to the method employed for
application to a substrate, but it should follow drying of the
primer layer. Drying is done according to a conventionally known
method (e.g., air drying, hot air drying, light irradiation and the
like).
[0163] According to the present invention, after UV irradiation,
the resulting UV insufficient area is subjected to UV irradiation
again within a specific amount of time to prevent occurrence of
defects of coating film, such as Tortoiseshell Pattern, Wrinkle,
Fog and the like. UV irradiation to a UV insufficient area may be
conducted several times, and UV irradiation can be applied to a
coating film having a UV insufficient area The "coating film having
UV insufficient area" means, for example, a coating film consisting
of UV insufficient area or a coating film consisting of UV
insufficient area and UV irradiation area and/or UV unirradiation
area. UV irradiation to a coating film having a UV insufficient
area is done preferably within 15 minutes, more preferably within 5
minutes, particularly preferably within 2 minutes, from the
previous UV irradiation.
[0164] When an ultraviolet curable coating agent is cured using an
ultraviolet irradiation apparatus, UV irradiation quantity during
curing is generally not less than 60 mJ/cm.sup.2 and not more than
10000 mJ/cm.sup.2, preferably not less than 150 mJ/cM.sup.2 and not
more than 3000 mJ/cm.sup.2. When the UV irradiation quantity is
less than 60 mJ/cm.sup.2, the coating film takes time to cure, and
when it exceeds 10000 mJ/cm.sup.2 the substrate and coating film
are adversely influenced to show discoloring and the like.
[0165] The ultraviolet irradiation apparatus and the method of
forming a cured coating film of the present invention can be
applied at any place, as long as the above-mentioned substrate of
the present invention is used, for example, wall, floor, table,
chairs and the like, and in a worksite, it is particularly
preferably used for a floor surface.
[0166] For example, an ultraviolet curable coating agent is applied
to a floor surface, and, using a moveable ultraviolet irradiation
apparatus, ultraviolet light is irradiated to cure the coating
film, whereby a cured coating film is formed. In addition, by using
the moveable ultraviolet irradiation apparatus of the present
invention, a coating can be applied to a substrate without a burn
or thermal deformation, even when the substrate is a floor material
made from a resin having low heat resistance, such as vinyl
chloride resin, polyolefin resin, polyester resin and the like.
EXAMPLES
[0167] The present invention is explained in more detail in the
following by referring to Examples that do not limit the present
invention in any way. In the following Examples and Comparative
Examples, "part(s)" means "part(s) by weight" unless particularly
indicated.
Example 1
[0168] An aqueous emulsion type urethaneacrylate resin (100 parts,
Arakawa Chemical Industries, Ltd.: EM-92) and photopolymerization
initiator (1 part, Ciba Specialty Chemicals: Darocur 0.1173) were
mixed uniformly in a stirrer and to give an ultraviolet curable
coating agent (A). This was applied on a polyester decorative
laminate in such a manner that the film thickness after curing
became 50 .mu.m and dried at ambient temperature for 130
minutes.
Example 2
[0169] An urethaneacrylate resin (50 parts, DAINIPPON INK AND
CHEMTCALS, INCORPORATED: UNIDIC 17-806), photopolymerization
initiator (0.8 part, Ciba Specialty Chemicals; Darocur 1173) and
ethyl acetate (30 parts) were mixed uniformly in a stirrer to give
an ultraviolet curable coating agent (B). This was applied on a
polyester decorative laminate in such a manner that the film
thickness after curing became 50 .mu.m and dried at ambient
temperature for 30 minutes.
Example 3
[0170] A urethaneacrylate resin (50 parts, SHIN-NAKAMURA CHEMICAL
CO., LTD.: U-15RA), a photopolymerization initiator (1 part, Ciba
Specialty Chemicals: Darocur 1173) and ethyl acetate (50 parts)
were mixed uniformly in a stirrer to give an ultraviolet curable
coating agent (C). This was applied on a polyester decorative
laminate in such a manner that the film thickness after curing
became 50 .mu.m and dried at ambient temperature for 30
minutes.
Example 4
[0171] A urethaneacrylate resin (6.3 parts, DAINIPPON INK AND
CHEMICALS, INCORPORATED: UNIDIC 17-806), an epoxy acrylate resin
(45 parts, DAICEL UCB COMPANY LTD.: EB-3404), a photopolymerization
initiator (0.5 part, Ciba Specialty Chemicals: Darocur 1173) and
ethyl acetate (46 parts) were mixed uniformly in a stirrer to give
an ultraviolet curable coating agent (D). This was applied on a
polyester decorative laminate in such a manner that the film
thickness after curing became 50 .mu.m and dried at ambient
temperature for 1 hour.
Example 5
[0172] An aqueous emulsion type top coating ultraviolet curable
coating agent (urethaneacrylate resin content 80%, GEN Maintenance
Technology Inc.: winup Topcoat T, catalyst:DBTDL) (E) was applied
on a composition vinyl chloride floor material coated with primer
(GEN Maintenance Technology Inc.: winup Undercoat U) in such a
manner that the film thickness after curing became 20 .mu.m and
dried at ambient temperature for 1 hour.
Example 6
[0173] An aqueous emulsion type urethaneacrylate resin (100 parts,
Arakawa Chemical Industries, Ltd.: EM-92) and a photopolymerization
initiator (1 part, Ciba Specialty-Chemicals: Darocur 1173) were
mixed uniformly in a stirrer to give an ultraviolet curable coating
agent (A). This was applied on a polyester decorative laminate in
such a manner that the film thickness after curing became 50 .mu.m
and dried at ambient temperature for 1 hour.
Comparative Example 1
[0174] An unsaturated polyester resin (50 parts, NIPPON KAYAKU CO.,
LTD.: PAR-500), a photopolymerization initiator (1 part, Ciba
Specialty Chemicals: Darocur 1173) and ethyl acetate (50 parts)
were mixed uniformly in a stirrer to give an ultraviolet curable
coating agent (F). This was applied on a polyester decorative
laminate in such a manner that the film thickness after curing
became 50 .mu.m and dried at ambient temperature for 30
minutes.
Comparative Example 2
[0175] An epoxy acrylate resin (50 parts, DAICEL UCB COMPANY LTD.:
EB-3404), a photopolymerization initiator (1 part, Ciba specialty
Chemicals: Darocur 1173) and ethyl acetate (50 parts) were mixed
uniformly in a stirrer to give an ultraviolet curable coating agent
(G). This was applied on a polyester decorative laminate in such a
manner that the film thickness after curing became 50 .mu.m and
dried at ambient temperature for 30 minutes.
[0176] The coating films made from the ultraviolet curable coating
agents obtained in the above-mentioned Examples and Comparative
Examples were cured using a moveable ultraviolet irradiation
apparatus (EYEGRAPHICS Co., Ltd.: W-100) with a low-pressure
mercury lamp and a moveable ultraviolet irradiation apparatus
(EYEGRAPHICS Co., Ltd.: L-100) with a high-pressure mercury lamp,
by UV irradiation for 5 seconds. UV irradiation quantity for curing
using each irradiation apparatus was 150 mJ/cm.sup.2 for
low-pressure mercury lamp, and 600 mJ/cm.sup.2 for high-pressure
mercury lamp.
[0177] Coating Film Property Test
[0178] After curing, the coating films of Examples 1-6 and
Comparative Examples 1-2, they were subjected to 3 hour spotting
using aqueous red ink (PILOT CORPORATION: ink red) and oil-based
black ink. The part spotted with aqueous red ink was washed with
water and the part spotted with oil-based black ink was wiped with
petroleum benzin. The extent of stain left on the coating film was
visually observed. The cured coating film of Example 5 was
subjected to evaluation of adhesiveness by crosscut cellotape
(registered trademark) peeling method. The results are shown in
Table 1.
[0179] Evaluation Criteria
[0180] .smallcircle.: the same level of coating film property
between curing with a low-pressure mercury lamp and curing with a
high-pressure mercury lamp.
[0181] .times.: inferior coating film property of curing with a
low-pressure mercury lamp than curing with a high-pressure mercury
lamp.
1 TABLE 1 Comparative Examples Examples 1 2 3 4 5 6 1 2 aqueous red
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. X X ink oil-based .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. X X black ink adhesiveness -- -- -- -- .largecircle.
-- -- --
Example 7
[0182] A coating film made from an ultraviolet curable coating
agent obtained in Example 5 was subjected to UV irradiation using a
moveable ultraviolet irradiation apparatus (EYEGRAPHICS Co., Ltd.:
W-100) with a low-pressure mercury lamp for 5 seconds. Immediately
after first UV irradiation and after 2 minutes, 5 minutes, 15
minutes and 30 minutes from the completion of the first UV
irradiation, ultraviolet light was irradiated again to UV
insufficient areas and occurrence of Tortoiseshell Pattern, Wrinkle
and Fog was visually observed and evaluated. The results are shown
in Table 2.
[0183] Evaluation Criteria
[0184] .smallcircle..smallcircle.: No occurrence of Tortoiseshell
Pattern, Wrinkle or Fog by visual observation from about 10 cm from
the film.
[0185] .smallcircle.: No occurrence by visual observation from
about 50 cm from the film, but occurrence of one of Tortoiseshell
Pattern, Wrinkle and Fog was observed from 10 cm from the film.
[0186] .DELTA.: Occurrence of one of Tortoiseshell Pattern, Wrinkle
and Fog was visually observed from not less than 50 cm from the
film.
[0187] .times.: occurrence of at least two of Tortoiseshell
Pattern, Wrinkle and Fog was visually observed from not less than
50 cm from the film.
Example 8
[0188] In the same manner as in Example 5 except that the
urethane(meth)acrylate resin obtained by changing the catalyst used
for urethane reaction to aluminum was used, the obtained coating
film was subjected to UV irradiation using a moveable ultraviolet
irradiation apparatus (EYEGRAPHICS Co., Ltd.: W-100) with a
low-pressure mercury lamp for 5 seconds. Immediately after first UV
irradiation and after 2 minutes, 5 minutes, 15 minutes and 30
minutes from the completion of the first UV irradiation,
ultraviolet light was irradiated again to UV insufficient areas and
occurrence of Tortoiseshell Pattern, Wrinkle and Fog was visually
observed and evaluated in the same manner as in Example 7. The
results are shown in Table 2.
2 TABLE 2 Second irradiation (Time from first First irradiation)
Irradiation 2 min 5 min 15 min 30 min Example 7
.largecircle..largecircle. .largecircle..largecirc- le.
.largecircle. .largecircle. X Example 8 .largecircle..largecirc-
le. .largecircle..largecircle. .largecircle..largecircle.
.largecircle..largecircle. .DELTA.
[0189] As is evident from the foregoing description, the present
invention provides a moveable ultraviolet irradiation apparatus
requiring an input power smaller than conventional ones, which can
improve workability and safety and permits miniaturization and
light-weight apparatus.
[0190] According to the method of the present invention, the
problems associated with the use of an ultraviolet irradiation
apparatus, whose light source is a high-pressure mercury lamp, can
be solved, such as the need of a high voltage power source,
degradation of quality, potential hazard to operators and the like,
and a cured coating film having the same properties as achieved by
the use of a high-pressure mercury lamp, as evidenced in stain
resistance, adhesion to substrate and the like, and requiring a
shorter time for curing of a unit area of the film as compared to
the use of a high-pressure mercury lamp (100 V type) can be
provided. Accordingly, the present invention is particularly useful
for floor surfaces of gymnasiums, classrooms, department stores,
offices, stores, showrooms and the like.
[0191] This application is based on application Nos. 2001-72686,
2001-79336, 2001-398486 and 2001-400816 filed in Japan, the
contents of which are incorporated hereinto by reference.
* * * * *